Bottom Line:
Little is known about the crystallographic effects of demineralization and remineralization.Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density.The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel.

Affiliation: Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.

ABSTRACTDental caries is the most prevalent disease encountered by people of all ages around the world. Chemical changes occurring in the oral environment during the caries process alter the crystallography and microstructure of dental enamel resulting in loss of mechanical function. Little is known about the crystallographic effects of demineralization and remineralization. The motivation for this study was to develop understanding of the caries process at the crystallographic level in order to contribute towards a long term solution. In this study synchrotron X-ray diffraction combined with scanning electron microscopy and scanning microradiography have been used to correlate enamel crystallography, microstructure and mineral concentration respectively in enamel affected by natural caries and following artificial demineralization and remineralization regimes. In particular, the extent of destruction and re-formation of this complex structure has been measured. 2D diffraction patterns collected at the European Synchrotron Radiation Facility were used to quantify changes in the preferred orientation (crystallographic texture) and position of the (002) Bragg reflection within selected regions of interest in each tooth slice, and then correlated with the microstructure and local mineral mass. The results revealed that caries and artificial demineralization cause a large reduction in crystallographic texture which is coupled with the loss of mineral mass. Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density. The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel. Combining microstructural and crystallographic characterization aids the understanding of caries and erosion processes and assists in the progress towards developing therapeutic treatments to allow affected enamel to regain structural integrity.

pone-0108879-g004: Changes in (002) Bragg peak position in a track (highlighted in Fig. 1) through each tooth slice (artificial demineralization, artificial remineralization, healthy control and natural caries) from enamel surface to EDJ.

Mentions:
Fig. 4 shows the percentage change in the (002) Bragg peak position as a function of distance from the natural tooth surface. There is very little change in peak position within each sample. A slight increase in the 2θ value is seen in the natural caries enamel from a 280 µm depth (<0.5%) onwards.

pone-0108879-g004: Changes in (002) Bragg peak position in a track (highlighted in Fig. 1) through each tooth slice (artificial demineralization, artificial remineralization, healthy control and natural caries) from enamel surface to EDJ.

Mentions:
Fig. 4 shows the percentage change in the (002) Bragg peak position as a function of distance from the natural tooth surface. There is very little change in peak position within each sample. A slight increase in the 2θ value is seen in the natural caries enamel from a 280 µm depth (<0.5%) onwards.

Bottom Line:
Little is known about the crystallographic effects of demineralization and remineralization.Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density.The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel.

Affiliation:
Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.

ABSTRACTDental caries is the most prevalent disease encountered by people of all ages around the world. Chemical changes occurring in the oral environment during the caries process alter the crystallography and microstructure of dental enamel resulting in loss of mechanical function. Little is known about the crystallographic effects of demineralization and remineralization. The motivation for this study was to develop understanding of the caries process at the crystallographic level in order to contribute towards a long term solution. In this study synchrotron X-ray diffraction combined with scanning electron microscopy and scanning microradiography have been used to correlate enamel crystallography, microstructure and mineral concentration respectively in enamel affected by natural caries and following artificial demineralization and remineralization regimes. In particular, the extent of destruction and re-formation of this complex structure has been measured. 2D diffraction patterns collected at the European Synchrotron Radiation Facility were used to quantify changes in the preferred orientation (crystallographic texture) and position of the (002) Bragg reflection within selected regions of interest in each tooth slice, and then correlated with the microstructure and local mineral mass. The results revealed that caries and artificial demineralization cause a large reduction in crystallographic texture which is coupled with the loss of mineral mass. Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density. The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel. Combining microstructural and crystallographic characterization aids the understanding of caries and erosion processes and assists in the progress towards developing therapeutic treatments to allow affected enamel to regain structural integrity.